Return a more suitable ref
Previously, the ref will always return an SVGGElement when the element's type is one of path, circle, line, rect, ellipse, polygon, polyline. Because we wrap these types of elements in an SVGGElement and return the SVGGElement as the ref.
Now, I have changed it to return the first path element of the SVGGElement.
It's just a better, not a perfect way to handle the ref. Because roughjs renders all shapes to SVGPathElement, we can't get the original ref.